In micromachining, there is a growing interest in pattern transfer over extreme topographies. The ability to pattern a sputtered layer on the bottom of an etched recess, tens to hundreds of micrometers deep or to make an electrical connection from the bottom to the top of such a recess improves the manufacturing abilities of any micromachining facility significantly. The procedure developed in this work is suitable for such purposes, can be implemented with completely standard micromachining equipment and works on any surface. It relies on the ultra-thick high aspect ratio resist SU-8 to fill up deep pits completely, using a modified spin coating procedure. A process is demonstrated that allows 20 um wide metal connections from the bottom to the top of a 250 um isotropically etched pit to be made. The process is compared with existing alternatives.
An important technological barrier in the development of microrobotic systems is the lack of compact sensor-actuator
systems. This paper presents a piston-cylinder fluidic microactuator with an integrated inductive position sensor. Such
positioning systems offer great opportunities for all devices that need to control a large number of degrees of freedom in
a restricted volume. The main advantage of fluidic actuators is their high force and power density at microscale. The
outside diameter of the actuator developed in this research is 1.3 mm and the length is 15 mm. The stroke is 12 mm, and
the actuation force is more than 0.4 N at a supply pressure of 550 kPa. The position sensor consists of two coils wound
around the cylinder of the actuator. The measurement principle is based on the change in coupling factor between the
coils as the piston moves in the actuator. The sensor is extremely small since one layer of 25 μm copper wire is sufficient
to achieve an accuracy of 10 μm over the total stroke. Measurements showed that the actuator achieves a positioning
accuracy of 20 μm in closed loop control.